1. Field of the Invention
The subject invention is directed to gas turbine engines, and more particularly, to systems for and methods of actively controlling pattern factor in gas turbine engines to optimize engine performance by improving fuel combustion, reducing emissions and increasing component longevity.
2. Background of the Related Art
Gas turbine engines typically include multiple fuel injectors arranged around a periphery of a combustion chamber. Depending on engine operating conditions, hot spots within the combustor can shorten the life of engine components, such as turbine blades. The overall spatial distribution of temperature within the combustor is referred to as the engine “pattern factor,” which can be defined as the difference between maximum combustor temperature (Tmax) and mean combustor exit temperature (T4) divided by the difference between the mean combustor exit temperature (T4) and the combustor inlet temperature (T3). That is:Pattern factor=[(Tmax−T4)/(T4−T3)]
Historically, passive measures were employed to modify pattern factor, for example by modifying the fuel injection distribution pattern or changing the shape or capacity of the combustion chamber. However, passive controls have proven to be costly and to limit combustor performance.
Moreover, fuel supplied to any of the multiple fuel injectors in a combustor is typically supplied via a common fuel manifold, without individual control of fuel flow through each injector. Applicants recognize that fuel pressure to and fuel flow rate through each injector can therefore be influenced by external conditions, to cause unequal fuel distribution about the circumference of the combustor, which then may result in an undesirably high pattern factor.
Applicants recognize therefore, that there is a need in the art for systems and methods to minimize pattern factor and thus promote longevity of engine components. The present invention provides solutions for this need.